JPS627378B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic control device for an internal combustion engine that electronically controls fuel supply to the internal combustion engine using a digital computer.

Conventionally, fuel injection systems have been known that control the fuel supply to an internal combustion engine by controlling the injection time of pressurized fuel, but when calculating the fuel injection amount using a digital computer, a clock signal with a constant frequency is counted. In particular, a conversion device such as a counter is required to convert the numerical data that is the calculated value into the valve opening time of the injector for fuel injection. and,
The amount of fuel required for an internal combustion engine is much higher during a cold start than during normal operation. However, when attempting to obtain such fuel supply characteristics by counting clock signals of a constant frequency in the counter of the converter, in order to obtain sufficient resolution, the counting capacity of the clock signal in the counter of the converter is required. The problem is that it has to be made larger. In other words, if the amount of fuel supplied during a cold start is required to be at least 10 times the maximum amount of fuel supplied during normal operation, the capacity of the counter that counts the clock signal should be increased from the capacity required during normal operation. This would require the use of multiple counters or large-capacity counters.

The present invention aims to provide an electronic control device for an internal combustion engine that can deal with the above-mentioned problems, and more specifically, it is an object of the present invention to provide an electronic control device for an internal combustion engine that can deal with the above-mentioned problems. By focusing on the points that occur in connection with specific operating conditions, including the cold start of an internal combustion engine, the conversion is achieved by lowering the frequency of the clock signal input to the converter in relation to the specific operating conditions. It is an object of the present invention to provide an electronic control device for an internal combustion engine, which allows the clock signal counting capacity of the device to be substantially expanded.

The present invention will be explained below based on an embodiment in which the present invention is applied to an internal combustion engine installed in a car. Although this embodiment shows that the ignition timing control for the internal combustion engine is also processed by a digital computer, it is not important for understanding the gist of the present invention, so a brief explanation will be provided.

In the overall configuration diagram shown in FIG. 1, 1 is a 6-cylinder 4-stroke internal combustion engine, 2 is a surge tank connected to an intake manifold, 3 is an intake cleaner, and 4 is an intake air amount and intake air temperature sensor. 5 is a throttle body, and 6 is a throttle sensor that interlocks with the throttle valve. Reference numeral 7 denotes an electromagnetic injector for fuel injection, which is provided for each cylinder of the internal combustion engine, and injects fuel with an electrically controlled valve opening time for fuel pumped at a predetermined pressure from a fuel system (not shown). Define the amount. 8 is an exhaust manifold, and 9 is an oxygen concentration sensor that detects the oxygen concentration in exhaust gas. 10 is a water temperature sensor that detects the temperature of the cooling water of the internal combustion engine, and 11 is a starting sensor that detects whether the engine starting electric motor is activated or not. 12 is an igniter, and 13 is a distributor, which has a built-in rotation sensor that generates a rotation pulse every time the output shaft rotates by 60 degrees. 14 is a control digital computer (hereinafter referred to as computer);
The ignition timing control of the automobile internal combustion engine and the arithmetic processing of the fuel injection control system are executed according to a predetermined program. In the above control system, input terminal devices for detecting input parameters include an intake air amount and intake air temperature sensor 4, a throttle sensor 6, an oxygen concentration sensor 9, a water temperature sensor 10, a starting sensor 11, and a distributor 13. A rotation sensor included in the injector 7 is connected as an input to the computer 14.
and the ignition igniter 12 is connected to the computer 14
It is connected as a controlled terminal device.

Next, the internal configuration of the computer 14 will be explained based on FIG. 2. Reference numeral 13a denotes a rotation sensor built into the distributor 13, which generates a pulse signal every 60 degrees, that is, an angle obtained by dividing the rotation angle of the engine output shaft into six equal parts including the top and bottom dead centers. Reference numeral 13b is a reference signal circuit which shapes a pulse signal every 60 degrees from the rotation sensor 13b into a waveform and distributes it to other devices. 15 is a processor that performs arithmetic processing according to a predetermined program, and a 12-bit common bus 1, for example, is used to input and output digital numerical data related to arithmetic processing and to issue operational commands to the input/output processing device.
6 is connected. Reference numeral 17 is a storage device (hereinafter referred to as memory) containing a program, and reference oscillator 18 is a reference oscillator that generates a clock signal for advancing the operation of the computer, and has a built-in frequency divider.

Reference numerals 19, 20, 21 and 28 are input processing devices for supplying various input information detected by the input terminal equipment to the common bus 16 as digital numerical data. Reference numeral 19 denotes a device for converting analog input into digital numerical data, which converts either the intake air amount and intake air temperature sensor 4 or the water temperature sensor 10, which generate analog signals among the input terminal devices, based on the instructions from the processor 15. It consists of an analog multiplexer that selects the selected analog signal and an analog-to-digital converter that converts the selected analog signal into digital numerical data. 20 is a device for processing digital inputs, which includes a signal from the throttle sensor 6 indicating whether the throttle valve is open or closed, a signal indicating whether the oxygen concentration in the exhaust gas is high or low from the oxygen concentration sensor 9,
and a storage device that stores signals from the starting sensor 11 indicating whether the starting motor is activated or not. Reference numeral 21 denotes a time width-to-clock number conversion device for converting engine rotation data into digital numerical data, which receives a pulse signal 13c every 60 degrees from the reference signal circuit 13b and counts a clock signal 18c of a predetermined frequency by that period. advance counter,
It consists of a memory circuit that stores count values. The counted value indicates the reciprocal value of the engine speed. 28 is an interrupt processing device which, when angle signals 13d and 13e indicating that the output shaft of the internal combustion engine is at a predetermined rotation angle is inputted from the reference signal circuit 13b, digital numerical data indicating the generation of this angle signal is inputted. , and requests the processor 15 to perform interrupt processing. Angle signal 1
3d and 13e are set to be generated from the reference signal circuit 13b at the timing when the calculation processing of the ignition timing and fuel injection amount in the processor 15 should be started by interrupt processing. Rotational pulses generated at dead center (0°), 120°, and 240° are used as angle signal 1 for calculating ignition timing.
3d, and the rotation pulse generated when the engine output shaft is 300 degrees from the top dead center is used as the angle signal 13e for calculating the fuel injection amount.

Reference numerals 22, 23, 24, and 25 are output processing devices that create operation signals for the controlled terminal equipment based on digital numerical data processed by the processor 15. 22 is an ignition control register, which is a device for converting digital numerical data necessary for ignition control into igniter operating time data directly involved in ignition control;
A latch temporarily stores digital numerical data given through the latch, and when a first angle signal 13f indicating an engine output shaft rotation angle of 60°, 180°, or 300° is given from the reference signal circuit 13b, the digital numerical data is temporarily stored in the latch. It is a down counter in which numerical data is set and the second angle signal 13g generated following the first angle signal 13f performs a subtraction calculation using a clock signal 18d of a predetermined frequency, and a borrow signal generated at the end of the down count Define the ignition point. Note that instead of the down counter, a combination of a counter that counts the clock signal 18d and a digital comparator that generates a coincidence signal when the count value of the latch and this counter match may be used. 24 is an amplification circuit that amplifies the borrow signal and supplies it to the ignition igniter 12. An ignition control system that uses the ignition control register 22 and the amplifier circuit 24 to set the ignition timing in the ignition igniter is known, for example, from Japanese Patent Application Laid-Open No. 52-54842 entitled "Ignition Timing Setting Device". Note that the ignition control register 22 constitutes a conversion device that converts numerical data into time data using a clock signal, but since the amount of change in ignition timing in an automobile internal combustion engine is generally small, in this case, the common bus 16
With the same 12-bit counting capacity, the ignition timing can be set with sufficient resolution using one clock signal 18d with a sufficiently fast frequency. Also, the rotation angle of the engine output shaft is at top dead center (0
The arithmetic processing started by the interrupt process at the rotation angles of 60°, 180° and 300° is already completed and stored in the latch.

23 is a fuel injection register, which is a device that converts digital numerical data indicating the fuel supply amount into injector operating time data that is directly involved in fuel supply amount control, temporarily stores the numerical data, and stores the stored numerical data. It consists of a down counter that performs subtraction counting based on a clock signal of a predetermined frequency from the reference oscillator 18, and uses the time during this counting as time data. 25 amplifies the signal indicating the time data and sends it to the injectors 7a and 7 of each cylinder.
This is an amplifier circuit that supplies As described above, this fuel control system is required to have a characteristic that the amount of fuel supplied during cold starting is much larger than the amount of fuel supplied during normal operation. Therefore, means are provided for selecting the frequency of the counting clock signal to satisfy this requirement. Reference numeral 26 denotes an analog switch that selectively switches between two clock signals of different frequencies from the reference oscillator 18 in accordance with instructions from the processor 15. 27 is a control device that creates control signals for peripheral devices including the input/output processing device according to instructions from the processor 15, and the switching signal 27a that instructs switching of the analog switch 26 is one of the control signals. be. Other control signal lines are omitted.

Next, a more detailed configuration of the fuel injection register 23 is shown in FIG. 3, and the fuel control system will be explained. 230 is a down counter that counts the fuel injection time that defines the fuel injection amount; 231 is an RS flip-flop that is set by the angle signal from the reference signal circuit 13b and reset by the down counter 230; R-
An AND gate 232 is a latch that temporarily stores a binary code signal. 1
6a indicates the fuel injection amount calculated by the processor 15, which is once stored in the latch 233 via the common bus 16 and then stored in the down counter 230.
Binary code signals 18a and 18b of fuel injection amount data are input to the reference oscillator 18, and two clock signals 27a and 27a have different frequency division ratios.
13h indicates a cold start, and a switching signal for switching the analog switch 26 to the lower frequency clock signal 18b, and 13h is a switching signal for transmitting data to the down counter 230 in order to prepare for the start of fuel injection from the reference signal 13b. load signal commanding the set,
13i is a start signal 23 that sets the Q output of the R-S flip-flop 231 immediately after the load signal 13h is generated in order to start fuel injection;
1a is an injection time signal that is generated at the Q output of the R-S flip-flop 231 and indicates the fuel injection of the injectors 7a and 7b; 232a is a clock signal passed through the analog switch 26 and the injection time signal 23;
A clock signal 230a is generated by performing a logical operation on the down counter 230 by the AND gate 232.
This is a borrow signal that is output when the contents of the down counter become 0 by sequentially decrementing the contents of the down counter. Then, a binary code signal 16a of fuel injection amount data
is determined by the processor 15 according to a predetermined program according to the following equation.

τ=Q/Ne・K ₁ +K ₂ −K ₃ …(1) τ=Q/Ne・K ₁ +K ₂ ′+K ₃ …(2) However, Q: intake air amount, Ne: engine speed,
K ₁ ; Proportionality constant determined by internal combustion engine capacity and model; K ₂ ; Cooling water temperature, oxygen concentration in exhaust gas,
This is a correction coefficient calculated based on input parameters such as intake air temperature and throttle opening degree, and when it is determined that a cold start is occurring, another correction coefficient K ₂ ' is calculated based on the input parameters. K ₃ ; Correction coefficient for correcting the driving voltage and invalid injection time of the solenoid valve. Note that the correction coefficients K ₂ and K ₂ ' are set in advance to satisfy the required fuel characteristics experimentally measured in each operating state of the internal combustion engine.
A proportionality constant determined by the frequency of the counting clock signal in down counter 230 is added.

Also, load signal 13h, start signal 13i
are output from the reference signal circuit 13h when the calculation of the fuel supply amount in the processor 15 has already been completed and the rotation angle of the engine output shaft is at the top dead center (0°). The switching signal 27a is output based on the determination by the processor 15 that a cold start is in progress.

Next, the operation of the fuel control system shown in FIG. 3 will be explained with reference to the time chart shown in FIG. 4. After the processor 15 outputs the fuel injection amount data 16a indicated by hatching in FIG. 4, 16a, the reference signal circuit 13b supplies the load signal 13h shown in FIG. 4, 13h to the down counter 230. The down counter 230 receives this load signal 13.
The fuel injection amount data 16a in binary code is read from the latch 233 and set in synchronization with h. Next, the start signal 13i shown in FIG. 413i is applied from the reference signal circuit 13b to the S input of the RS flip-flop 231, and its Q output signal, that is, the injector injection signal 231a, is set to "1". This injection signal 231a shown in FIG. 4 231a passes through the amplifier circuit 25, opens the injectors 7a and 7b, and starts injection of pressurized fuel into the internal combustion engine. On the other hand, when injection signal 231a is set to "1", AND gate 232 applies constant frequency clock signal 18a or 18b from reference oscillator 18 to the clock input of down counter 230, as shown in FIG. 4, 232a.
The down counter 230 receives the injection amount data 16a that has been set in advance each time this clock signal is input.
is subtracted one count at a time, and when the set number of subtractions is completed, that is, the measurement of the injection time is completed, the down counter 230 outputs a borrow signal 230a shown in FIG. 4, 230a, and resets the RS flip-flop 231. Therefore, the set state duration time of the RS flip-flop 231 and the subtraction time of the down counter 230 match, and this time is proportional to the fuel injection amount. When the R-S flip-flop 231 is reset, the injection signal 231a, which is its Q output, is reset to "0", so the fuel injection of the injectors 7a and 7b, which were opened through the amplifier circuit, is stopped.
This means that the defined amount of fuel has been injected into the internal combustion engine.

The difference between normal operation and cold start of the internal combustion engine is that the subtraction frequency of the down counter 230 is switched. When the processor 15 determines that the cold start operation is being performed,
At that point the switching signal 27 shown in FIG. 4 27a
a is applied to the analog switch 26, which selects the reference oscillator 18 clock signal 18b. Regarding the frequencies of the two clock signals 18a and 18b emitted from the reference oscillator 18, the clock signal 18a is used to convert the fuel injection amount data in normal operation, that is, the numerical data determined by the above formula, into the required fuel injection time. The other clock signal 18b is the fuel injection amount data in the cold start operation, that is, the
It is set to convert the numerical data determined by equation (2) into the required fuel injection time. In any conversion, the counting capacity of the down counter 230 is used to obtain sufficient resolution, so naturally the clock signal 18b is the same as the clock signal 1.
The frequency is lower than 8a. The frequency of clock signal 18a is 160KHz, and the frequency of clock signal 18b is 160KHz.
When set to 10KHz, the down counter 23
Even if the clock signal count value of 0 is the same, the time from the start of counting to the end of counting by the down counter 230 is inversely proportional to the frequency of the clock signal being counted, so the normal clock signal frequency is 160K.
If a frequency of 10 KHz, which is 1/16 of Hz, is used, it is possible to give the internal combustion engine 16 times the fuel injection time, that is, the fuel injection amount during a cold start.

Next, the overall flow of operation in the above configuration will be explained. First, when the computer 14 turns on the power of the vehicle, the reference oscillator 18 generates various clock signals, and the processor 15 is stored in the memory 17 based on the signals. Start operation according to the program. And analog input processing device 19
The engine cooling water temperature is taken in as an analog signal from the water temperature sensor 10 through the converter, and then converted from analog to digital into 12-bit digital numerical data, which is then sent to the processor 15 through the common bus 16.
be taken in. The digital numerical data taken into the processor 15 is temporarily stored in the memory 17 through the common bus 15. Similarly, the intake air amount and intake air temperature to the internal combustion engine are also taken in from the sensor 10 via the input processing device 19 and stored in the memory 17.
is memorized.

Next, when the starting motor is energized by a starting operation of the internal combustion engine, a starter operation signal is stored in the digital input processing device 20 from the starting sensor 11.
The commands from the processor 15 are input to the processor 15 through the common bus 16. When the starter operation signal is input to the processor 15, the processor 15 determines that the starter is currently being started. Then, the engine cooling water temperature temporarily stored in the memory 17 is read out from the memory 17 and compared with a predetermined set value. If the cooling water temperature is below the set value, it is determined that a cold start is to be performed. Thereby, a switching signal 27a is applied to the analog switch 26 to instruct switching of the clock signal, and the fuel injection register 23
The counting clock signal in the down counter 230 is determined to be the 10 KHz clock signal 18b.
On the other hand, the rotation pulse signal from the rotation sensor 13a is converted into digital numerical data by counting a constant clock signal 18c for a period of time indicating a constant rotation angle of the engine output shaft in a time width/clock number conversion device 21. 15 through the common bus 16, and then the memory 17
is temporarily stored.

The processor 15 reads out from the memory 17 the input parameters necessary for calculating the fuel injection amount data at the time of cold start according to the equation (2), and executes the calculation according to the equation (2). The fuel injection amount data obtained as a result of calculation is 2
is a forward code signal and is set in latch 233 in fuel injection register 23. Similarly, the processor 15 also controls the engine cooling water temperature,
Calculation is performed according to a predetermined calculation formula from the intake air amount, intake air temperature, engine rotation signal (engine rotation signal from the starter), etc., and numerical data indicating ignition timing data is used for ignition control via the common bus 16, and the data stored in the register 22 is Set to latch. The base point for setting the ignition timing and the starting point for fuel injection based on the numerical data set in these latches are determined at a predetermined position of the rotation angle of the engine output shaft, and an angle signal indicating this position, that is, generated by the rotation sensor 13a, is determined. Angle signals 13f, 13g, and 13 separated by the reference signal circuit 13b based on rotation pulses every 60°
h, 13i are directly input to the ignition control register 22 and the fuel injection register 23.

In the fuel injection register 23, a load signal 13h and an angle signal 1 as a start signal 13i are input.
The numerical data is converted into valve opening time data based on 3h and 13i, and the amplifier circuit 25 and injector 7
Fuel is injected into the intake manifold through ports a and 7b. This burial time is determined by the 10KHz clock signal 18b.
This is the time until the decrement count value matches the fuel injection amount data set in the down counter 230 at the time of cold start.

Further, in the ignition control register 22, the first
Numerical data is converted into ignition timing data based on the generation of the angle signal 13f and the second angle signal 13g, and ignites an ignition plug (not shown) through the amplifier circuit 24 and the igniter 12.

On the other hand, when the starter operation signal from the starting sensor 11 disappears after the starting has been completed, the processor 15 determines that normal operation is in progress and executes the calculation of the fuel injection data during normal operation as shown in equation (1) above. At the same time, the switching signal 27a applied to the analog switch 26 is eliminated, so the down counter 2
The numerical data set to 30 is erased by the 160 KHz clock signal 18a. Therefore, even if the fuel injection amount data set in the down counter 230 are calculated values of similar magnitude during a cold start and during normal operation, the clock signal 18a, The actual amount of fuel injected can be made different by the frequency difference of 18b,
That is, both the amount of fuel required during cold start and during normal operation can be supplied by one injector.

When restarting the internal combustion engine immediately after normal operation, the engine cooling water temperature detected by the water temperature sensor 10 is higher than the preset temperature, so the processor 15 determines that the engine is in normal operation since it is starting but not in a cold state. and perform calculation processing.

In the ignition control system, the ignition timing is changed within a certain range both during cold start and during normal operation, so the internal configuration of the ignition control register 22 is not changed; Only the numerical data set is changed.

According to the embodiment of the present invention described in detail above,
It is understood that large changes in the amount of fuel required to be supplied in an internal combustion engine installed in an automobile can be coped with by using one injector for each cylinder and changing its valve opening time significantly. In the above-described embodiment, the frequency of the clock signal is selected by switching the analog switch 26 in the conversion device 23 that converts digital numerical data into time data, but other means may be used. In place of the switch 26, it is equipped with a frequency divider circuit that operates on the command signal 27a, and the frequency is 160KHz from the reference oscillator 18.
The command signal 27a is input by inputting the clock signal 18a of
An output of 10KHz may be generated when . Further, by selecting three or more clock signals, it is easy to obtain a configuration that can cope with even greater changes in operating time, based on the disclosure of the above-described embodiments. For example, in the fuel supply control device shown in the above-described embodiment, when a large amount of fuel is required to be supplied during normal driving, for example, when sudden acceleration is performed while increasing the amount of warm air, even when the amount of warm air is being increased. The required fuel can be supplied by selecting a clock signal with a lower frequency based on the determination of .

As described above, in the present invention, for a conversion device such as a counter that converts digital numerical data calculated by a digital computer and fuel supply time, the frequency of the clock signal is selected to a low value in a specific state of the internal combustion engine. By adding a configuration for this purpose, the capacity of the converter can be substantially expanded without using a converter with a particularly large counting capacity for cold starting, and the frequency selection can be performed on an internal combustion engine. Since it is automatically performed in relation to the operating state of the engine, it has the excellent effect of being able to cope with operations involving large changes in fuel supply amount.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention, and FIG. 2 is a computer 1 in the apparatus shown in FIG.
Figure 3 is a block diagram showing the detailed configuration of Figure 4.
FIG. 4 is a block diagram showing the detailed configuration of the fuel control system in the illustrated computer, and FIG. 4 is a time chart for explaining the operation of the fuel control system shown in FIG. 3. DESCRIPTION OF SYMBOLS 1... Internal combustion engine, 7... Injector for fuel supply, 10, 11... Water temperature sensor for detecting a specific state, starting sensor, 15... Digital processor serving as calculation means, 23... Fuel injection register serving as a conversion device, 26... Analog switch for frequency selection.

Claims (1)

[Claims] 1 Calculating means for digitally calculating the amount of fuel required according to the operating state of the internal combustion engine according to a predetermined program; and a digital numerical value indicating the fuel amount generated by the calculating means by counting clock signals of a predetermined frequency. converting means for converting data into a pulse signal of a corresponding time width; fuel supply means for supplying fuel to the internal combustion engine in response to the pulse signal from the converting means; detection means for detecting a specific state including;
The present invention is characterized by comprising a selection means for selecting a lower frequency as the frequency of the clock signal input to the converting means when the specific state is detected by the detecting means than when the specific state is not detected. Electronic control unit for internal combustion engines.